Question

Modify the client server system program given below so that instead of sendto() and recvfrom(),

you use connect() and un-addresssed write() and read() calls.

//Server.c

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

# define PortNo 4567

# define BUFFER 1024

int main(int argc, char ** argv) {

int ssd;

int n;

socklen_t len;

char msg[BUFFER];

char clientmsg[BUFFER];

struct sockaddr_in server;

struct sockaddr_in client;

int max_iterations = 0;

int count = 0, totalChar = 0, i = 0;

if (argc != 2) {

printf("%s \n", argv[0]);

return -1;

}

if ((ssd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {

perror("failed to create socket");

exit(EXIT_FAILURE);

}

memset( & server, 0, sizeof(server));

   server.sin_family = AF_INET;

server.sin_addr.s_addr = INADDR_ANY;

server.sin_port = htons(PortNo);

  

if (bind(ssd, (const struct sockaddr * ) & server,

   sizeof(server)) < 0) {

perror("failed to bind");

exit(EXIT_FAILURE);

}

while (max_iterations++ < atoi(argv[1])) {

len = sizeof(client);

   n = recvfrom(ssd, msg, BUFFER, 0, (struct sockaddr * ) & client, & len);

if (n < 0) {

perror("While calling recvfrom()");

exit(EXIT_FAILURE);

}

printf("Client Message Received: %s\n", msg);   

while (clientmsg[i] != '\0') {

if (clientmsg[i] == ' ') {

totalChar;

} else

totalChar++;

i++;

}

  

printf("\nNumber of characters: %d", totalChar);

sendto(ssd, clientmsg, n, 0, (struct sockaddr * ) & client, len);

}

      return 0;

}

//Client.c

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

# define PortNo 4567

# define BUFFER 1024

int main(int argc, char * argv[]) {

int ssd;

int n;

socklen_t len;

char sendline[BUFFER];

char receiveline[BUFFER];

struct sockaddr_in server;

  

printf("Enter the message to server : ");

scanf("%s", sendline);

ssd = socket(AF_INET, SOCK_DGRAM, 0);

memset( & server, 0, sizeof(server));

  

server.sin_family = AF_INET;

server.sin_addr.s_addr = INADDR_ANY;

server.sin_port = htons(PortNo);

  

len = sizeof(server);

sendto(ssd, sendline, BUFFER, 0, (struct sockaddr * ) & server, len);

  

n = recvfrom(ssd, receiveline, BUFFER, 0, NULL, NULL);

receiveline[n] = '\0';

printf("Echo servers message is: %s\n", receiveline);

   close(ssd);

return 0;

}

Answer 1

In these client server programs I have used Connect and read , write system calls. These port numbers and other parameters or libraries and header file are as per my system configurations, you can change these parameters as per your system specifications.

Server.c

#include<stdio.h>
#include<netinet/in.h>
#include<netdb.h>
#include<unistd.h>
#define SERV_TCP_PORT 5035
int main(int argc,char**argv)
{
int sockfd,newsockfd,clength;
struct sockaddr_in serv_addr,cli_addr;
char buffer[4096];
sockfd=socket(AF_INET,SOCK_STREAM,0);
serv_addr.sin_family=AF_INET;
serv_addr.sin_addr.s_addr=INADDR_ANY;
serv_addr.sin_port=htons(SERV_TCP_PORT);
printf("\nStart");
bind(sockfd,(struct sockaddr*)&serv_addr,sizeof(serv_addr));
printf("\nListening...");
printf("\n");
listen(sockfd,5);
clength=sizeof(cli_addr);
newsockfd=accept(sockfd,(struct sockaddr*)&cli_addr,&clength);
printf("\nAccepted");
printf("\n");
read(newsockfd,buffer,4096);
printf("\nClient message:%s",buffer);
write(newsockfd,buffer,4096);
printf("\n");
close(sockfd);
return 0;
}

Client.c

#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#include<unistd.h>
#include <arpa/inet.h>
#define SERV_TCP_PORT 5035
int main(int argc,char*argv[])
{
int sockfd;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[4096];
sockfd=socket(AF_INET,SOCK_STREAM,0);
serv_addr.sin_family=AF_INET;
serv_addr.sin_addr.s_addr=inet_addr("127.0.0.1");
serv_addr.sin_port=htons(SERV_TCP_PORT);
printf("\nReady for sending...");
connect(sockfd,(struct sockaddr*)&serv_addr,sizeof(serv_addr));
printf("\nEnter the message to send\n");
printf("\nClient: ");
fgets(buffer,4096,stdin);
write(sockfd,buffer,4096);
printf("Serverecho:%s",buffer);
printf("\n");
close(sockfd);
return 0;
}